Plants start to flower when young?

My plants flower about 3 weeks from surfacing, please help.
They are given lots of tlc and are fed a supplement.
I also have one more problem my dogs love the plants and are serious space cakes, but i know that is my own fault.
thanx.

ok i am new at this out door growing thing..hell im new to growing.i was wondering..there is this old abandoned green house by my house. i have seev bugz in it and some animal dropping but i could make it to no people or animals could get it. its very old becuase other plants have been growing.and every once in a while when its hot here it gets like 100 degrees in there! i dont know if growing is a good idea. i want to save the rest of my seeds and plant two sensi skunks but i dont if its an outdoorsy type.since in the past alot of peoples have gotten into the place im going to get a liock that they cant pick and inside is a blue garbage bin .i was wondering to chop down the amount of pests and bugs could i plant it in there?i am scured that it may die of mites or something.and the heat may kill it.can SOME ONE HELP ME PLEASE??!!

Sorry bout that, now let's see.
The plant is a sativa grown from seed and is outside in half a 25l drum (don't know the gallon equivalent), it gets about 12h of sunlight and is protected from the wind by shade netting. I've covered it with a 5l clear, bottomless plastic bottle as this creates a mini-greenouse while the plant is young. Now the problem if I grow a few seedlings and wait for them to mature to sort out the male and female plants then my females end up flowering when they aren't even 20cm off the ground. They form a few flowers and a few seed and then die. I don't know if I am waiting too long to separate the male and female plants or if there is another factor?
Thanx again

Old School

If what you say about the light is true....the reason they are flowering is because they flower with 12 hours of sunlight and 12 hours of darkness!....hope that solves you're problem....Peace out....Sid